[PATCH 06/14] iomap: Support THPs in iomap_is_partially_uptodate

Matthew Wilcox (Oracle)
2020-10-14T09:20:57Z

Factor iomap_range_uptodate() out of iomap_is_partially_uptodate() to use
by iomap_readpage() later. iomap_is_partially_uptodate() can be called
on a tail page by generic_file_buffered_read(), so handle that correctly.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
fs/iomap/buffered-io.c | 43 ++++++++++++++++++++++++------------------
1 file changed, 25 insertions(+), 18 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 4633ebd03a3f..4ea6c601a183 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -141,6 +141,24 @@ static void iomap_adjust_read_range(struct inode *inode, struct page *page,
*lenp = plen;
}

+static bool iomap_range_uptodate(struct inode *inode, struct page *page,
+ size_t start, size_t len)
+{
+ struct iomap_page *iop = to_iomap_page(page);
+ size_t first = start >> inode->i_blkbits;
+ size_t last = (start + len - 1) >> inode->i_blkbits;
+ size_t i;
+
+ VM_BUG_ON_PGFLAGS(!PageLocked(page), page);
+ if (!iop)
+ return false;
+
+ for (i = first; i <= last; i++)
+ if (!test_bit(i, iop->uptodate))
+ return false;
+ return true;
+}
+
static void
iomap_iop_set_range_uptodate(struct page *page, unsigned off, unsigned len)
{
@@ -446,26 +464,15 @@ int
iomap_is_partially_uptodate(struct page *page, unsigned long from,
unsigned long count)
{
- struct iomap_page *iop = to_iomap_page(page);
- struct inode *inode = page->mapping->host;
- unsigned len, first, last;
- unsigned i;
-
- /* Limit range to one page */
- len = min_t(unsigned, PAGE_SIZE - from, count);
+ struct page *head = thp_head(page);
+ size_t len;

- /* First and last blocks in range within page */
- first = from >> inode->i_blkbits;
- last = (from + len - 1) >> inode->i_blkbits;
+ /* 'from' is relative to page, but the bitmap is relative to head */
+ from += (page - head) * PAGE_SIZE;
+ /* Limit range to this page */
+ len = min(thp_size(head) - from, count);

- if (iop) {
- for (i = first; i <= last; i++)
- if (!test_bit(i, iop->uptodate))
- return 0;
- return 1;
- }
-
- return 0;
+ return iomap_range_uptodate(head->mapping->host, head, from, len);
}
EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate);

--
2.28.0